50 



Dr. Tracy E. Hazen gave an interesting lecture on "Tetra- 

 sporopsis, a genus new to American algology, and its phylo- 

 gentic significance." 



Dr. Edmund W. Sinnott gave a talk on "Factors determin- 

 ing the size and shape of the vascular system in fern petioles." 



In certain ferns the leaf trace as it leaves the stele is rela- 

 tively small but increases markedly in size, sometimes as much 

 as ten times, in its course through the base of the petiole. Trans- 

 piration can hardly be a factor in determining this difference 

 s'nce the transpiration stream seems to be accommodated 

 equally well by the small leaf trace and the large petiolar bun- 

 dle. The difference is most marked in types like Osmunda, 

 where the petiole is encased for some distance in a mass of firm 

 leaf bases. The petiole is much constricted at the base and 

 reaches its maximum size as it becomes free. The size of the 

 vascular system of the petiole roughly parallels that of the 

 petiole itself. In types where the rhizome is superficial and the 

 petiole springs directly from it, as in Polypodium, there is no 

 constriction either of the petiole or of its vascular system. It is 

 suggested that size differences in the petiolar vascular system 

 are not primarily due to functional stimuli but are correlated 

 with the general development of the petiole, which seems to de- 

 pend both upon its freedom to expand and upon the necessity 

 for considerable mechanical rigidity at the point where it be- 

 comes free. 



Respectfully submitted, 



Forman T. McLean 

 Secretary 



Meeting of February 2, 1932 



The meeting was called to order at the American Museum 

 of Natural History at 8 : 15 p.m. by President Sinnott with sixty- 

 nine members present. 



The following were unanimously elected to membership in 

 the club:|Mr. Sidney Charles Bausor, 18 Crescent Road, Larch- 

 mont, New York; Mr. Robert I. Rashby, 2144 Bronx Park, 

 East, Bronx, New York City; Dr. M. A. Raines, Dept. Botany, 

 Howard University, Washington, D. C. 



The resignations of Miss Trotman C. Barrow, Mr. Roland 

 Jackson Hunter, Mr. Nazzareno Palleri, Mr. Alexander F. 



